MIMO Antenna Elevation Detection via Offset Arrays
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Solution Overview
Problem
Current automotive radar systems can only determine distance and horizontal angle to a target, lacking elevation angle detection, which is crucial for avoiding obstacles like bridges or buildings, and increasing the number of antennas to improve elevation resolution significantly increases system cost.
Innovation Solution
A MIMO antenna configuration with vertically offset transmit-antenna arrangements allows for elevation angle determination without increasing the number of transmit or receive antennas, using a virtual-receive antenna with half-wavelength spacing to avoid grating lobes and maintain cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of transmit-antennas and receive-antennas is increased to improve elevation resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a vertical dimension to the antenna array configuration by vertically offsetting transmit-antenna arrangements. This dimensional change enables elevation angle determination without requiring additional antennas in the traditional sense, as the vertical spacing creates virtual receive-antenna elements that provide elevation resolution while maintaining a compact antenna count
Solution Approach 2:
The patent creates virtual receive-antenna arrangements through the vertical offset of transmit-antenna arrangements. These virtual copies enable elevation detection functionality without physically duplicating the entire antenna system, thereby improving measurement precision while avoiding proportional increases in device complexity and cost
2Power
If parallel arrays are used to increase antenna gain, then power is improved, but grating lobes cause harmful factors to increase
Solution Approach 1:
The patent applies different spacing configurations to different parts of the antenna system. Specifically, the vertical offset distance between transmit-antenna arrangements is set to half-wavelength or less, while horizontal spacing maintains orthogonality. This localized quality differentiation allows the system to achieve high gain through vertical coherence while suppressing grating lobes through controlled spacing
Solution Approach 2:
The patent changes the spacing parameter from traditional uniform spacing to a differentiated spacing scheme where vertical offset distance is specifically controlled (half-wavelength or less) while horizontal spacing maintains orthogonality. This parameter change enables the system to achieve high antenna gain through coherent combining while suppressing grating lobe formation by keeping spacing below the grating lobe threshold
3Object-affected harmful factors
If sub-arrays are overlapped to reduce phase-center spacing, then grating lobes are reduced, but device complexity increases
Solution Approach 1:
Instead of overlapping sub-arrays in the horizontal plane which requires complex multi-layer feed structures, the patent achieves the equivalent effect by introducing vertical offset between transmit-antenna arrangements. This dimensional change creates virtual receive-antenna elements with appropriate spacing without requiring physical overlap or complex feed networks
Solution Approach 2:
The patent creates virtual receive-antenna arrangements through vertical offset of transmit-antenna arrangements, eliminating the need for physical sub-array overlap and complex multi-layer feed structures. This virtual copying approach achieves grating lobe suppression while maintaining feed structure simplicity
Data Source
AI summary
A multiple input multiple output (MIMO) antenna for a radar system includes a receive antenna, a first transmit-antenna-arrangement, and a second transmit-antenna-arrangement. The receive-antenna is configured to detect radar-signals reflected by a target toward the receive-antenna. The first transmit-antenna-arrangement includes a first vertical-array of radiator elements and a second vertical-array of radiator elements. The first transmit-antenna-arrangement is configured so the first vertical-array can be selectively coupled to a transmitter independent of the second vertical-array. The second transmit-antenna-arrangement includes a third vertical-array of radiator elements and a fourth vertical-array of radiator elements. The second transmit-antenna-arrangement is configured so the third vertical-array can be selectively coupled to a transmitter independent of the fourth vertical-array. The second transmit-antenna-arrangement is vertically offset from the first transmit-antenna-arrangement by a vertical offset distance selected so an elevation angle to the target can be determined by the receive-antenna.